Non-Contact Torque Monitoring for Rotary Electric Machines
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Solution Overview
Problem
Monitoring the operation of electrical rotating machines without frequency converters or motor management systems requires high metrological effort, and existing methods often necessitate structural changes or invasive measurements.
Innovation Solution
A non-contact sensor system measures electromagnetic fields and rotor vibrations outside the machine housing to determine state variables like torque and mechanical power, using magnetic field sensors and acceleration sensors, with data transmitted wirelessly to a cloud for processing, allowing for retrofitted implementation without affecting the machine's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a special torque sensor is mounted on the shaft to determine output torque, then measurement precision is improved, but device complexity and ease of manufacture deteriorate due to structural changes
Solution Approach 1:
The patent replaces mechanical torque sensors mounted on the shaft with a magnetic field-based measurement system. The stator's magnetic field is measured outside the machine housing using magnetic sensors, and torque is calculated from the magnetic field strength and rotor position data, eliminating the need for mechanical contact and structural modifications to the shaft or rotor.
Solution Approach 2:
The patent introduces magnetic field measurements as an intermediary between the stator and the measurement system. By measuring the magnetic field generated by the stator windings outside the machine housing and correlating it with rotor position, the system indirectly determines torque without direct mechanical measurement, thus avoiding structural changes.
2Measurement precision
If current transformers and evaluation electronics are used to measure motor current, then measurement precision is improved, but device complexity worsens due to additional components
Solution Approach 1:
The patent replaces electrical current measurement using current transformers with magnetic field sensing. By measuring the magnetic field strength and rotor position outside the machine housing, the system calculates torque and power directly from magnetic parameters, eliminating current transformers and complex evaluation electronics for current decomposition.
3Reliability
If infrared temperature sensors are used for non-contact temperature measurement, then reliability is improved, but ease of operation worsens due to alignment requirements
Solution Approach 1:
The patent replaces infrared temperature sensors with magnetic field sensors for non-contact measurement. Magnetic sensors can measure the stator's magnetic field from various positions outside the machine housing without requiring precise alignment, as magnetic field strength varies predictably with position and load, eliminating the alignment constraints of optical infrared sensors.
4Measurement precision
If state variables are determined using invasive measurement methods, then measurement precision is improved, but ease of manufacture deteriorates due to structural modifications
Solution Approach 1:
The patent uses the stator's magnetic field as an intermediary that can be measured outside the machine housing. By placing magnetic sensors on the external surface of the machine housing, the system accesses internal operational parameters (torque, power, speed) through the magnetic field without penetrating or modifying the machine structure, enabling easy retrofitting while maintaining measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables accurate determination of state variables without structural changes, reducing the need for on-machine data processing and storage, thus enhancing monitoring efficiency and ease of retrofitting.
Implementation Method 1
an electromagnetic field of the stator is measured as the first physical variable
Implementation Method 2
a vibration behavior of the rotor is measured as the second physical variable
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for monitoring the operation of an electrical rotating machine (2) comprising a rotor (8), a stator (10), and a machine housing (18), in which the rotor (8) and the stator (10) are accommodated. In order to allow the method to be carried out without structural changes to the electrical rotating machine (2), according to the invention, outside the machine housing (18) a first physical value of the stator (10) and a second physical value of the rotor (8) is measured, wherein at least one state variable of the electrical rotating machine (2) is determined from the first physical value and the second physical value.